The only possible candidates for this would be either Javanese or Sundanese kingdom (Majapahit or Pajajaran), since they were the ones that were advanced, populous, and homogenous enough to be the best Japan-analogue of the region. But since they were not remotely as isolated as Japan, they will likely become less successful at it, being geographically more vulnerable to European economic imperialism.
Prevent Paregreg Civil War. It set a terrible precedent for continuous military competition for kingship between royal children that seriously exhausted and de-consolidated the Majapahit empire. Had a lasting stability reigned over instead, Java would've had become a more advanced and burgeoning urban society, in comparable level with East Asian Sinicized countries. They won't stay thalassocratic hegemon (and thus, Hindus) permanently, but a plain chance to rebound later on.